Perceptual processing delays between attribute dimensions (e.g. color, form and motion) (Moutoussis & Zeki, 1997a) have been attributed to temporal processing asynchronies resulting from functional segregation of visual information (Livingstone & Hubel, 1988; Zeki, 1973). Although the direction of asynchrony is largely in agreement across these studies (a perceptual advantage for both colour and form over motion) they differ in magnitude (Moutoussis and Zeki, 1997a; 1997b; Arnold et al, 2001; Viviani and Aymoz, 2001; Nishida & Johnston, 2002). To account for the discrepancies between the perceptual asynchronies that are reported between these studies we previously suggested a flexible rather than fixed account of attribute processing and consequently of perceptual asynchrony (Paul and Schyns, 2003). In the current study we have attempted to unify two research traditions to try and resolve these discrepancies. To this end, we turned to findings in the categorisation literature to account for apparent inconsistencies in the perceptual asynchrony literature. Specifically, it seems that participants can selectively attend to an attribute that is relevant for the task at hand (e.g. Oliva and Schyns, 1997). Research has demonstrated a perceptual advantage when the values of an attribute can be easily discriminated (e.g. Goldstone, 1994). Previous research has suggested that attention can independently modulate attributes (Paul and Schyns, 2003). Therefore, the current study set out to examine whether we could modulate perceptual processing and consequently perceptual asynchrony by manipulating the discriminability of two attributes, namely colour and spatial frequency. Results suggest that the perceptual processing of these attributes is flexible, moreover, the perceptual asynchrony between them was also modulated by the requirements of the task.